// Copyright (c) 2003 Daniel Wallin and Arvid Norberg

// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:

// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
// ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
// TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
// PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
// SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
// ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
// ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
// OR OTHER DEALINGS IN THE SOFTWARE.

// hacked by Cloudage at 2009,to fix the lua stack breaking issue of getupvalue_fix,and find some way to determin wether the upvalue exists.

#pragma once
#include <luabind/object.hpp>

namespace luabind
{
	template <class ValueWrapper>
	inline object getupvalue_fix(ValueWrapper const& value, int index)
	{		
		lua_State* interpreter = value_wrapper_traits<ValueWrapper>::interpreter(
			value
			);
		//int count = lua_gettop(interpreter);

		value_wrapper_traits<ValueWrapper>::unwrap(interpreter, value);		
		//count = lua_gettop(interpreter);
		const char* getupvalueret = lua_getupvalue(interpreter, -1, index);
		//count = lua_gettop(interpreter);
		detail::stack_pop pop(interpreter, getupvalueret==0?1:2);
		return object(from_stack(interpreter, -1));
	}

	template <class ValueWrapper>
	inline bool upvalue_not_exists(ValueWrapper const& value, int index)
	{		
		lua_State* interpreter = value_wrapper_traits<ValueWrapper>::interpreter(
			value
			);
		//int count = lua_gettop(interpreter);

		value_wrapper_traits<ValueWrapper>::unwrap(interpreter, value);		
		//count = lua_gettop(interpreter);
		bool not_exists = lua_getupvalue(interpreter, -1, index)==0;
		//count = lua_gettop(interpreter);		 
		detail::stack_pop pop(interpreter, not_exists?1:2);
		return not_exists;
	}
}